Friday, April 30, 2010
Reliably Replicating Phenotype
I will preface this journal entry with an admission: I understand very little about equine genetics.
I do comprehend the difference between genotype (the inherited genetic information) and phenotype (the environmentally influenced observable results of how inherited genes express themselves morphologically, physiologically and behaviorally).
Genetically, the Sorraia and the Sorraia Mustang horses do not have an unadulterated lineage that can, definitively lay claim to them being a "pure breed", and, to my knowledge, no one involved with the preservation of the Sorraia horses has made such claims. These horses do not represent a "breed", though they are often referred to as such. Some researchers understand the Sorraia to reflect an ancestral "form" of primitive equine, most likely the Southern Iberian variant of the Tarpan (Equus ferus).
The Tarpan is thought to have dwelled in as diverse regions as France, Iberia and Russia and likely many others with phenotypical variations relating to the environments they existed within--thus we hear of the "Forest Tarpan" and the "Steppe Tarpan".
The last remaining Tarpan died in 1876.
Some descriptions tell of variants that had convex profiles, others had concave...some had upright manes, others had falling manes. Some were a bit shorter, others a bit taller--but they all were fine limbed with well articulated tapered heads and all were considered "mouse dun" in colour, with hues ranging from very light (almost white) to very dark (almost black) and as such they had prominent dorsal stripes and often stripes on their legs and shoulders and bi-coloured manes and tails.
My understanding is the Tarpan represented a genetic subspecies of wild equine and expressed variations in phenotype relating to which ever environment it adapted itself to and it was distinctly different than the wild Asiatic horse (Przewalski's Horse). In prehistoric cave paintings we find not only images remarkably similar to Przewalski's Horse, but also to the Tarpan in both its variant forms, one looking more like the Celtic pony and the other looking much more like the Sorraia. Incidentally, the medieval Iberians described striped wild horses of like characteristics that lived in their region and they called them Zebros.
Here at the Ravenseyrie Sorraia Mustang Preserve, our desire has been to assist in the preservation of the genetically bottlenecked Sorraia--the indigenous wild horse of southern Spain and Portugal--(dare I say the Iberian Tarpan?) by assembling a small group of North American mustang mares from various Iberian-influenced strains that each possess Sorraia characteristics and crossing them with a purebred Sorraia to enhance genetic variability.
Our foundation mares are:
--Ciente, a "purebred" Kiger Mustang
--Bella, a "purebred" Spanish Mustang
--Belina, part Spanish Mustang/part feral Appaloosa Mustang pony
--Zorita, part Sorraia/part Sulphur Mustang
Our Sorraia stallion, Altamiro and his harem of Sorraia Mustang mares are this year presenting us with their third "foal crop" which so far shows such remarkable uniformity among them and the first two years' offerings, one cannot help but conceive that the phenotype of the Iberian Tarpan is alive and well--testifying to the strength of the ancestral genetics that remain in present day horses and were just waiting for the right environment to consolidate the way this particular phenotypical expression manifests itself.
For me, this validates several assumptions regarding the Sorraia and the Sorraia type mustang...they must have a genetic link, more determinable than mtDNA and that the reliable reproducibility demonstrated here at Ravenseyrie suggests that pairing "like with like" regardless of "pedigree" is a valuable means of approaching preservation (at least for primitive horse forms) when environmental conditions are as close to a wild habitat as possible.
Throughout this journal entry, I've been treating you to photos of Belina and Altamiro's third filly!
She was born yesterday afternoon.
Mother and baby are in good form, and Altamiro looks after them with the firm diligence we've come to expect.
As soon as we discover what name this filly finds acceptable, I will post it to the blog.
I will end by saying I don't mind that I am scientifically illiterate--for me the visual manifestation of our preservation efforts speaks volumes and needs no peer-reviewed study to demonstrate that the the genetics of the prehistoric wild European horses have not been totally lost.
How fitting that an ancestral horse form that originally evolved in North America, went extinct here in its homeland, but survived in Europe and and is perilously close to disappearing there, has found consolidation so readily back in North America as demonstrated here at the Ravenseyrie Sorraia Mustang Preserve. I hope others will engage in this type of preservation to further consolidate and protect a form of horse that transcends time and space.
Please write me if you are interested in establishing a preserve on a tract of suitable land. I can put you in touch with people who have excellent examples of Sorraia Mustangs and those who have purebred Sorraia horses. Email: firstname.lastname@example.org